JP6981915B2 - Endoscope optical system and endoscope - Google Patents

Description

The present invention relates to an optical system for an endoscope and an endoscope provided with the optical system for the endoscope.

Conventionally, in the medical field, an insertion type endoscope in which a long insertion portion having an imaging device built in a tip portion is inserted through the mouth or nose of a subject to image the inside of a body cavity has become widespread. Further, in recent years, an endoscope capable of both direct vision and side vision has been proposed. As an optical system for an endoscope used for an endoscope capable of both direct viewing and lateral viewing, for example, those described in the following Patent Documents 1 to 4 are known.

Special Table 2016-521607 Gazette Japanese Patent No. 6000223 Japanese Unexamined Patent Publication No. 2008-309860 International Publication No. 17/110351

The endoscope optical system described in Patent Documents 1 to 3 has a problem that it is difficult to visually recognize the image of the side view region because the image of the side view region is formed around the image of the direct view region.

Since the endoscope optical system described in Patent Document 4 can individually acquire two types of images, that is, a direct view region and a side view region, it is possible to obtain a highly visible image. However, the endoscope optical system described in Patent Document 4 switches between the direct-view optical path and the side-view optical path to individually acquire two types of images, that is, the direct-view region and the side-view region. It is not possible to perform both visions at the same time, and there is a problem that observation efficiency is poor.

The present invention has been made in view of the above circumstances, and includes an endoscope optical system capable of acquiring two types of images of a direct view region and a side view region individually and simultaneously, and an optical system for the endoscope. The purpose is to provide an endoscope.

The optical system for an endoscope of the present invention is an optical system for an endoscope capable of both direct viewing and lateral viewing, and has a first lens group used only for direct viewing and a negative lens on the most object side. , A plurality of second lens groups used only for lateral viewing, a third lens group shared for direct viewing and lateral viewing, and a light beam emitted from the second lens group transmitted through the light beam emitted from the first lens group. A compositing unit that has at least one reflective planar composite surface, and combines the light beam emitted from the first lens group and the light beam emitted from the second lens group by the composite surface to be incident on the third lens group. The light beam emitted from the first lens group and the light beam emitted from the second lens group are imaged on the same surface, and the second lens group has two or more negative lenses continuously from the object side. Has .

Further, it is preferable that one surface on which the composite surface is formed is a partially transmitted and partially reflective surface.

Further, it is preferable that the third lens group has a third a-junction lens in which a positive lens and a negative lens are joined in order from the object side on the image side.

Further, it is preferable that the first lens group has a first a-junction lens in which a positive lens and a negative lens are joined in order from the object side.

Further, when the focal length of the first lens group is f1 and the combined focal length of the first lens group and the third lens group is F1, it is preferable that the conditional equation (2) is satisfied. It is more preferable to satisfy the following conditional expression (2-1).
-1.5 <f1 / F1 <-1.1 ... (2)
-1.45 <f1 / F1 <-1.15 ... (2-1)

Further, when the focal length of the third lens group is f3 and the combined focal length of the first lens group and the third lens group is F1, it is preferable that the conditional equation (3) is satisfied. It is more preferable to satisfy the following conditional expression (3-1).
5 <f3 / F1 <12 ... (3)
7 <f3 / F1 <10 ... (3-1)

When the third a junction lens is provided in the third lens group, the conditional expression is used when the Abbe number of the positive lens of the thirda junction lens is νd31 and the Abbe number of the negative lens of the thirda junction lens is νd32. It is preferable to satisfy (4). It is more preferable to satisfy the following conditional expression (4-1).
38 <νd31-νd32 <58 ... (4)
40 <νd31-νd32 <56 ... (4-1)

Further, when the third a junction lens is provided in the third lens group, the refractive index of the positive lens of the thirda junction lens is n31, and the refractive index of the negative lens of the thirda junction lens is n32. It is preferable to satisfy (5). It is more preferable to satisfy the following conditional expression (5-1).
-0.45 <n31-n32 <-0.28 ... (5)
-0.43 <n31-n32 <-0.3 ... (5-1)

Further, in the case where the first a junction lens is provided in the first lens group, the conditional expression when the Abbe number of the positive lens of the first a junction lens is νd11 and the Abbe number of the negative lens of the firsta junction lens is νd12. It is preferable to satisfy (6). It is more preferable to satisfy the following conditional expression (6-1).
-40 <νd11-νd12 <-10 ... (6)
-38 <νd11-νd12 <-12 ... (6-1)

Further, it is preferable that the composite surface is tilted with respect to the axis perpendicular to the optical axis of the third lens group.

The endoscope of the present invention is provided with the above-described optical system for an endoscope of the present invention.

The optical system for an endoscope of the present invention is an optical system for an endoscope capable of both direct viewing and lateral viewing, and has a first lens group used only for direct viewing and a negative lens on the most object side. , A plurality of second lens groups used only for lateral viewing, a third lens group shared for direct viewing and lateral viewing, and a light beam emitted from the second lens group transmitted through the light beam emitted from the first lens group. A compositing unit that has at least one reflective planar composite surface, and combines the light beam emitted from the first lens group and the light beam emitted from the second lens group by the composite surface to be incident on the third lens group. Since the light beam emitted from the first lens group and the light beam emitted from the second lens group are imaged on the same plane, two types of images, a direct view region and a side view region, are separately imaged. It is possible to provide an optical system for an endoscope that can be acquired at the same time, and an endoscope provided with the optical system for the endoscope.

Sectional drawing which shows the structure of the optical system for an endoscope (common with Example 1) which concerns on one Embodiment of this invention. Optical path diagram of the optical system for an endoscope according to the first embodiment. Schematic configuration of the synthesis unit of the endoscope optical system of Example 1 above. Sectional drawing which shows the structure of the optical system for an endoscope of Example 2 of this invention. Optical path diagram of the optical system for an endoscope according to the second embodiment. Each aberration diagram of the optical system for an endoscope according to the first embodiment of the present invention. Each aberration diagram of the optical system for an endoscope according to the second embodiment of the present invention. Schematic block diagram of an endoscopic observation system according to an embodiment of the present invention Schematic diagram of an image obtained by an endoscope according to an embodiment of the present invention. The figure which shows the display example of the endoscope image in the said endoscope observation system. The figure which shows the display example of the endoscope image in the said endoscope observation system. The figure which shows the display example of the endoscope image in the said endoscope observation system. The figure which shows the display example of the endoscope image in the said endoscope observation system. The figure which shows the display example of the endoscope image in the said endoscope observation system. The figure which shows the display example of the endoscope image in the said endoscope observation system.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing the configuration of an optical system for an endoscope according to an embodiment of the present invention, FIG. 2 is an optical path diagram of the optical system for an endoscope, and FIG. 3 is a synthesis of the optical system for an endoscope. It is a schematic block diagram of a part. The configuration examples shown in FIGS. 1 and 2 are common to the configuration of the endoscope optical system of the first embodiment described later. In FIGS. 1 and 2, when the optical path is expanded, the left side is the object side and the right side is the image side, and the aperture stop St shown in the figure does not necessarily represent the size or shape, and is on the optical axis Z. It indicates the position. Further, in FIG. 2, both the direct-viewing and lateral-viewing optical paths (the axial luminous flux A1 and the maximum luminous flux A2 and A3 in the direct-viewing, the axial luminous flux B1 and the maximum luminous flux B2 in the left-sided view) are shown in the upper row. B3, the axial luminous flux C1 in the right side view and the maximum luminous flux C2, C3) are shown, and the optical path only for direct viewing (the axial luminous flux A1 and the maximum luminous flux A2, A3 in the direct view) is shown in the middle row, and the lower row shows. Shows the optical path only for the left side view (the axial luminous flux B1 and the maximum luminous flux B2 and B3 in the left side view).

Note that FIGS. 1 and 2 show an example in which an optical member PP having an incident surface and an emitted surface parallel to each other is arranged between the endoscope optical system and the image plane Sim. The optical member PP assumes an optical path conversion prism, a filter, and / or a cover glass for bending an optical path, and in the present invention, the optical member PP can be omitted.

The optical system for an endoscope of the present embodiment is an optical system for an endoscope capable of both direct viewing and lateral viewing, and has a first lens group G1 used only for direct viewing and a negative lens on the most object side. The second lens group G2L and G2R which are used only for lateral vision, the third lens group G3 which is shared by direct vision and lateral vision, and the second lens group G2L which transmits the light beam emitted from the first lens group G1. , Has a planar composite surface XS1 and XS2 that reflects the light beam emitted from the G2R, and is emitted from the light beam emitted from the first lens group G1 and the second lens group G2L and G2R by the composite surface XS1 and XS2. It consists of a compositing unit X that combines the light beam and incidents it on the third lens group G3, and the light beam emitted from the first lens group G1 and the light beam emitted from the second lens group G2L and G2R are imaged on the same plane. It is configured to be. In the endoscope optical system of the present embodiment, the two second lens groups G2L and G2R have exactly the same lens configuration, but the plurality of second lens groups may have different lens configurations.

As shown in FIG. 3, in the composite unit X, three prisms P1, P2, and P3 are joined, a composite surface XS1 is formed on the boundary surface between the prisms P1 and P2, and the composite surface XS1 is synthesized on the boundary surface between the prisms P1 and P3. The surface XS2 is formed. The composite surfaces XS1 and XS2 are half mirror surfaces that are partially transmitted and partially reflected surfaces. The composite surfaces XS1 and XS2 are configured to be tilted by 36.0 ° with respect to the optical axis Z3 of the third lens group G3.

Here, it is preferable that one surface on which the synthetic surface XS1 or the synthetic surface XS2 is formed is a partially transmitted and partially reflective surface. In this way, by forming a partially transmissive partially reflective surface on the entire surface instead of forming a partially transmissive partially reflective surface on a part of one surface, the composite unit X It can be easy to manufacture.

The luminous flux emitted from the first lens group G1 (luminous flux from the direction A in FIG. 3) is transmitted to the third lens group G3 side via the compositing unit X, but is emitted from the first lens group G1 at this time. Since the luminous flux passes through the composite surface XS1 or the composite surface XS2 once, the amount of light is reduced to 1/2. Further, the luminous flux emitted from the second lens group G2L (the luminous flux from the B direction in FIG. 3) is deflected toward the third lens group G3 by the compositing unit X, but is emitted from the second lens group G2L at this time. Since the luminous flux passes through the synthetic surface XS1 and is reflected by the synthetic surface XS2, the amount of light is reduced to 1/4. Similarly, the luminous flux emitted from the second lens group G2R (luminous flux from the C direction in FIG. 3) is also deflected toward the third lens group G3 by the compositing unit X, but at this time, it is emitted from the second lens group G2R. Since the light flux is transmitted through the composite surface XS2 and then reflected by the composite surface XS1, the amount of light is reduced to 1/4. As described above, the effect of the decrease in the amount of light caused by passing through the synthesis unit X is mitigated by correcting the image signal acquired by the image sensor when the endoscope optical system is incorporated into the endoscope. be able to.

The angle of inclination of the composite surfaces XS1 and XS2 with respect to the optical axis Z3 of the third lens group G3 is not particularly limited, but is inclined with respect to the axis perpendicular to the optical axis Z3 of the third lens group G3 (first). It is preferable that the lens group is not tilted by 90 ° with respect to the optical axis Z3 of the lens group G3). With such a configuration, the image height in the averted vision region can be adjusted.

Further, the partially transmitted partially reflective surface on the composite surfaces XS1 and XS2 is not limited to the half mirror surface having the same transmittance and the reflectance, and may be a surface having different transmittance and reflectance.

Further, the number of synthetic surfaces possessed by the synthetic unit is not limited to two, and may be one or a plurality of three or more.

As described above, the optical system for an endoscope of the present embodiment shares a part of the lens group (third lens group G3) between the optical system required for direct viewing and the optical system required for lateral viewing. It is possible to reduce the size and cost of the entire optical system for an endoscope.

Further, with respect to the second lens groups G2L and G2R used only for lateral viewing, by providing a negative lens on the most object side, the lateral viewing region can be widened.

Further, a compositing unit X is provided to synthesize the light beam emitted from the first lens group G1 for direct viewing and the light beam emitted from the second lens groups G2L and G2R for lateral viewing, and both direct viewing and lateral viewing are performed. By configuring the light beams to be imaged on the same plane, only one image pickup element is required when the endoscope optical system is incorporated into the endoscope, so that the inside including the endoscope optical system is included. It is possible to reduce the size and cost of the entire endoscope. In addition, it is possible to simultaneously observe a plurality of directions in the direct viewing direction and the lateral viewing direction.

Further, instead of forming an image of the side-viewing region around the image of the direct-viewing region, two types of images of the direct-viewing region and the side-viewing region are acquired individually and simultaneously, so that the side-viewing region can be easily seen widely. It is possible to further improve the observation efficiency.

In the endoscope optical system of the present embodiment, it is preferable that the second lens group G2L and G2R have two or more negative lenses continuously from the object side. With such a configuration, the negative refractive power required for widening the second lens group G2L and G2R can be dispersed among a plurality of negative lenses, so that the occurrence of various aberrations can be suppressed.

Further, it is preferable that the third lens group G3 has a third a-junction lens in which a positive lens and a negative lens are joined in order from the object side on the image side. Such a configuration is advantageous in suppressing chromatic aberration of magnification and axial chromatic aberration.

Further, it is preferable that the first lens group G1 has a first a-junction lens in which a positive lens and a negative lens are joined in order from the object side. Such a configuration is advantageous in suppressing chromatic aberration of magnification.

Further, when the focal length of the second lens group G2L, G2R is f2 and the combined focal length of the second lens group G2L, G2R and the third lens group G3 is F2, it is preferable to satisfy the conditional expression (1). .. Curvature of the image plane can be suppressed by making sure that the value does not fall below the lower limit of the conditional expression (1). By not exceeding the upper limit of the conditional expression (1), the angle of view can be maintained while suppressing the diameter of the lens. If the conditional expression (1-1) is satisfied, better characteristics can be obtained.
-0.95 <f2 / F2 <-0.1 ... (1)
-0.9 <f2 / F2 <-0.15 ... (1-1)

Further, when the focal length of the first lens group G1 is f1 and the combined focal length of the first lens group G1 and the third lens group G3 is F1, it is preferable that the conditional equation (2) is satisfied. Curvature of the image plane can be suppressed by making sure that the value does not fall below the lower limit of the conditional expression (2). By not exceeding the upper limit of the conditional expression (2), the angle of view can be maintained while suppressing the diameter of the lens. If the conditional expression (2-1) is satisfied, better characteristics can be obtained.
-1.5 <f1 / F1 <-1.1 ... (2)
-1.45 <f1 / F1 <-1.15 ... (2-1)

Further, when the focal length of the third lens group G3 is f3 and the combined focal length of the first lens group G1 and the third lens group G3 is F1, it is preferable that the conditional equation (3) is satisfied. By making sure that the angle does not fall below the lower limit of the conditional expression (3), it is possible to suppress the angle of incidence on the image pickup element when the endoscope optical system is incorporated into the endoscope. The curvature of field can be suppressed by not exceeding the upper limit of the conditional expression (3). If the conditional expression (3-1) is satisfied, better characteristics can be obtained.
5 <f3 / F1 <12 ... (3)
7 <f3 / F1 <10 ... (3-1)

Further, when the third a junction lens is provided in the third lens group G3, the condition is that the Abbe number of the positive lens of the third a junction lens is νd31 and the Abbe number of the negative lens of the thirda junction lens is νd32. It is preferable to satisfy the formula (4). Chromatic aberration of magnification can be suppressed by making sure that the value does not fall below the lower limit of the conditional expression (4). By preventing the amount from exceeding the upper limit of the conditional expression (4), axial chromatic aberration can be suppressed. If the conditional expression (4-1) is satisfied, better characteristics can be obtained.
38 <νd31-νd32 <58 ... (4)
40 <νd31-νd32 <56 ... (4-1)

Further, when the third a junction lens is provided in the third lens group G3, the condition is that the refractive index of the positive lens of the thirda junction lens is n31 and the refractive index of the negative lens of the thirda junction lens is n32. It is preferable to satisfy the formula (5). Spherical aberration can be suppressed by making sure that the amount does not fall below the lower limit of the conditional expression (5). The curvature of field can be suppressed by not exceeding the upper limit of the conditional expression (5). If the conditional expression (5-1) is satisfied, better characteristics can be obtained.
-0.45 <n31-n32 <-0.28 ... (5)
-0.43 <n31-n32 <-0.3 ... (5-1)

Further, in the case where the first a junction lens is provided in the first lens group G1, the condition is that the Abbe number of the positive lens of the first a junction lens is νd11 and the Abbe number of the negative lens of the first a junction lens is νd12. It is preferable to satisfy the formula (6). By satisfying the conditional expression (6), chromatic aberration of magnification can be suppressed. If the conditional expression (6-1) is satisfied, better characteristics can be obtained.
-40 <νd11-νd12 <-10 ... (6)
-38 <νd11-νd12 <-12 ... (6-1)

Next, numerical examples of the optical system for an endoscope of the present invention will be described. First, the endoscope optical system of Example 1 will be described. FIG. 1 shows a cross-sectional view showing the configuration of the endoscope optical system of Example 1, and FIG. 2 shows an optical path diagram of the endoscope optical system of Example 1. In FIGS. It does not represent the shape, but shows the position on the optical axis Z. Further, in FIG. 2 and FIG. 5 corresponding to the second embodiment described later, both the direct-viewing and lateral-viewing optical paths (the axial luminous flux A1 and the maximum luminous flux A2 and A3 in the direct-viewing, and the axis in the left-sided view) are shown in the upper row. The upper luminous flux B1 and the maximum luminous flux B2 and B3, the axial luminous flux C1 in the right side view and the maximum luminous flux C2 and C3) are shown, and the optical path only for direct viewing (the axial luminous flux A1 and the maximum image in direct viewing) is shown in the middle stage. The angular luminous fluxes A2 and A3) are shown, and the optical path only for the left side view (the axial luminous flux B1 and the maximum angled luminous flux B2 and B3 in the left side view) are shown in the lower row.

The optical system for an endoscope of Example 1 includes a first lens group G1 used only for direct viewing, a second lens group G2L and G2R used only for lateral viewing, and a third lens group shared for direct viewing and lateral viewing. It has a G3 and planar composite surfaces XS1 and XS2 that transmit the light beam emitted from the first lens group G1 and reflect the light beam emitted from the second lens groups G2L and G2R. It is composed of a compositing unit X that synthesizes the light beam emitted from the first lens group G1 and the light beam emitted from the second lens groups G2L and G2R and causes the light beam to be incident on the third lens group G3.

The first lens group G1 is composed of three lenses, a lens L1a to a lens L1c. The positive lens L1b and the negative lens L1c are joined to form a first a junction lens CL1a.

The second lens group G2L and G2R have the same lens configuration, and each of them is composed of three lenses, a lens L2a to a lens L2c.

The third lens group G3 is composed of an aperture stop St and five lenses, a lens L3a to a lens L3e. The positive lens L3d and the negative lens L3e are joined to form a third a junction lens CL3a.

The composite surfaces XS1 and XS2 of the composite unit X are half mirror surfaces.

Table 1 shows the basic lens data of the direct-view optical path of the optical system for the endoscope of Example 1, data on the specifications of the direct-view optical path is shown in Table 2, and the basic lens data of the side-view optical path is shown in Table 3. The data on the specifications are shown in Table 4. Hereinafter, the meanings of the symbols in the table will be described by taking the example of Example 1 as an example, but the same is basically true for Example 2.

In the lens data of Tables 1 and 3, the surface number column shows the surface number that increases sequentially toward the reduction side with the surface of the component on the most enlarged side as the first, and the curvature radius column shows the curvature of each surface. The radius is shown, and the distance between each surface and the next surface on the optical axis Z is shown in the surface spacing column. Further, the column n indicates the refractive index of each optical element at the d-line (wavelength 587.6 nm (nanometer)), and the column ν indicates the d-line of each optical element (wavelength 587.6 nm (nanometer)). The Abbe number in. The sign of the radius of curvature is positive when the surface shape is convex on the enlargement side and negative when the surface shape is convex on the reduction side. The basic lens data includes the half mirror surface, the aperture stop St, and the optical member PP. In the column of the surface number of the surface corresponding to the half mirror surface, the phrase (half mirror) is described together with the surface number. Further, in the column of the surface number of the surface corresponding to the aperture stop St, the phrase (aperture) is described together with the surface number.

The data related to the specifications in Tables 2 and 4 include the focal length f and the F number FNo. , The value of the total angle of view 2ω (°) is shown.

In the basic lens data and data related to specifications, ° is used as the unit of angle and mm (millimeter) is used as the unit of length, but the optical system can be used even if it is expanded or contracted proportionally. Other suitable units can also be used.

FIG. 6 shows each aberration diagram of the optical system for an endoscope according to the first embodiment. Spherical aberration, non-point aberration, and chromatic aberration of magnification in the direct-viewing optical path are shown in order from the left side of the upper row in FIG. Spherical aberration, non-point aberration, and chromatic aberration of magnification are shown on the side, and spherical aberration, non-point aberration, and magnification are shown on the object side of the optical axis Z2L / Z2R of the second lens group G2L / G2R of the side-viewing path in order from the lower left side. Shows chromatic aberration.

Each aberration diagram showing spherical aberration and astigmatism shows aberrations with the d-line (wavelength 587.6 nm (nanometer)) as a reference wavelength. In the spherical aberration diagram, the aberrations for the d line (wavelength 587.6 nm (nanometer)), C line (wavelength 656.3 nm (nanometer)), and F line (wavelength 486.1 nm (nanometer)) are shown as solid lines. , Long broken line, and short broken line. The astigmatism diagram shows aberrations in the sagittal and tangential directions with solid lines and short dashed lines, respectively. The chromatic aberration of magnification diagram shows aberrations for line C (wavelength 656.3 nm (nanometers)) and line F (wavelength 486.1 nm (nanometers)) with long and short dashed lines, respectively. In addition, FNo. Means F number, and ω in other aberration diagrams means a half angle of view.

Next, the endoscope optical system of Example 2 will be described. FIG. 4 shows a cross-sectional view showing the configuration of the endoscope optical system of Example 2, and FIG. 5 shows an optical path diagram of the endoscope optical system of Example 2. The endoscope optical system of the second embodiment has the same number of lenses as the endoscope optical system of the first embodiment. Further, the basic lens data of the direct-view optical path of the optical path for the endoscope of the second embodiment is shown in Table 5, the data regarding the specifications of the direct-view optical path is shown in Table 6, and the basic lens data of the side-viewing optical path is shown in Table 7. The data on the specifications of the optical path are shown in Table 8, and each aberration diagram is shown in FIG.

Table 9 shows the values corresponding to the conditional expressions (1) to (6) of the endoscope optical system of Examples 1 and 2. In all the examples, the d line is used as the reference wavelength, and the values shown in Table 9 below are at this reference wavelength.

From the above data, all the optical systems for endoscopes of Examples 1 and 2 satisfy the conditional equations (1) to (6), and have good optical performance while having a direct view region and a side view region. It can be seen that the optical system for an endoscope is capable of acquiring the two types of images individually and simultaneously.

Next, an embodiment of an endoscope to which the optical system for an endoscope of the present invention is applied will be described with reference to FIG. 8 is a schematic configuration diagram of an endoscope observation system equipped with the endoscope, FIG. 9 is a schematic diagram of an image acquired by the endoscope, and FIGS. 10 to 15 are endoscopy in the endoscope observation system. It is a figure which shows the display example of a mirror image.

The endoscope 100 shown in FIG. 8 mainly includes an operation unit 102, an insertion unit 104, and a universal cord 106 connected to a connector unit (not shown). Most of the insertion portion 104 is a soft portion 107 that bends in an arbitrary direction along the insertion path, a curved portion 108 is connected to the tip of the flexible portion 107, and a tip portion 110 is connected to the tip of the curved portion 108. Has been done. The bending portion 108 is provided to direct the tip portion 110 in a desired direction, and the bending operation can be performed by rotating the bending operation knob 109 provided on the operation portion 102. The endoscope optical system 1 according to the embodiment of the present invention is arranged at the inner tip of the tip portion 110. FIG. 8 schematically illustrates the endoscope optical system 1.

Two types of images, a direct view region and a side view region, acquired by the endoscope optical system 1 are formed on an image pickup surface of an image pickup device (not shown). The output signals from the image pickup element regarding these images are arithmetically processed by the signal processing device 120 and displayed as an endoscopic image on the display device 130.

Here, two types of images, a direct view region and a side view region, which are imaged on the image pickup surface of the image pickup device, will be described. As shown in FIG. 1, the endoscope 100 provided with the endoscope optical system 1 according to the embodiment of the present invention has a direct viewing region (direction A in FIG. 1) and a left side viewing region (direction B in FIG. 1). ), And a circular image in three directions of the right side viewing region (C direction in FIG. 1) can be acquired at the same time.

At this time, each image is formed on the image pickup surface of the image pickup device in the form shown in FIG. In FIG. 9, in order to make the explanation easy to understand, the character A is schematically described for the image ID of the direct view region, the character B is schematically described for the image ISL of the left side view region, and the image ISR of the right side view region is described. The letter C is schematically described with respect to.

In the endoscope optical system 1 according to the embodiment of the present invention, the luminous flux emitted from the first lens group G1 (luminous flux in the direct viewing region) is transmitted to the third lens group G3 side via the synthesis unit X. However, at this time, the luminous flux emitted from the first lens group G1 passes through the composite surface XS1 or the composite surface XS2 once, so that the amount of light is reduced to 1/2.

Further, the luminous flux emitted from the second lens group G2L (the luminous flux in the left side viewing region) is deflected toward the third lens group G3 side by the compositing unit X, but at this time, the luminous flux emitted from the second lens group G2L. Is transmitted by the synthetic surface XS1 and then reflected by the synthetic surface XS2, so that the amount of light is reduced to 1/4. Further, since the luminous flux in the left side viewing region is reflected by the composite surface XS2, the image ISL itself in the left side viewing region is inverted left and right when an image is formed on the image pickup surface of the image pickup device, as shown in FIG. , And an image is formed on the right side of the image ID in the direct viewing region.

The luminous flux emitted from the second lens group G2R (luminous flux in the right side viewing region) is also deflected toward the third lens group G3 by the compositing unit X, but at this time, the luminous flux emitted from the second lens group G2R is synthesized. After passing through the surface XS2, it is reflected by the composite surface XS1, so that the amount of light is reduced to 1/4. Further, since the luminous flux in the right side viewing region is reflected by the composite surface XS1, when an image is formed on the imaging surface of the image pickup device, the image ISR itself in the right side viewing region is inverted left and right as shown in FIG. , And the image is formed on the left side of the image ID in the direct viewing region.

The signal processing device 120 performs left-right inversion processing on the image GSL of the image ISL in the left side viewing region, and displays it on the left side of the image GD in the direct viewing region. Further, the image GSR of the image ISR in the right-viewing region is subjected to left-right inversion processing and displayed on the right side of the image GD in the direct-viewing region. Further, as described above, since the amount of light differs twice between the image ID in the direct view region, the image ISL in the left side view region, and the image ISR in the right side view region, the image GD in the direct view region and the image GSL in the left side view region The brightness adjustment process is performed so that the brightness is about the same as that of the image GSR in the right side viewing region.

As a result, as shown in FIG. 10, the image GD in the direct view region, the image GSL in the left side view region, and the image GSR in the right side view region can be made into an image with correct arrangement and uniform brightness.

As for the image generated by the signal processing device 120, as shown in FIG. 11, in order to make the connection between the direct view and the side view natural, the image GD in the direct view region, the image GSL in the left side view region, and the right side view region are used. The image GSR may be overlapped and displayed. The amount of overlap may be appropriately adjusted, for example, by overlapping the range from the edge of each image to 5%.

Further, as shown in FIG. 12, for an image group in which the image GD in the direct viewing region, the image GSL in the left side viewing region, and the image GSR in the right side viewing region are overlapped, the upper, lower, left, and right ends are rectangular. May be cut out and displayed.

Further, as shown in FIG. 13, even if the overlap region is cut out and displayed for the image group in which the image GD in the direct view region, the image GSL in the left side view region, and the image GSR in the right side view region are overlapped. good.

Further, as shown in FIG. 14, the positional relationship between the side view and the direct view is sensuously related to the image group in which the image GD in the direct view region, the image GSL in the left side view region, and the image GSR in the right side view region are overlapped. In order to make it easy to understand, the display may be provided with a perspective corresponding to the positional relationship between the direct viewing region and the lateral viewing region.

Since the endoscope of the present embodiment includes the endoscope optical system 1, it is possible to acquire two types of images, a direct viewing region and a lateral viewing region, individually and simultaneously.

Although the present invention has been described above with reference to embodiments and examples, the present invention is not limited to the above embodiments and examples, and various modifications are possible. For example, the radius of curvature, the interplanar spacing, the refractive index, and the Abbe number of each lens are not limited to the values shown in the above embodiment, and other values can be taken.

Further, in the endoscope optical system of the above embodiment, an example in which two second lens groups are provided is shown as an example, but the number of the second lens groups is not limited to two, and three or more lens groups are used. May be good.

Specifically, four second lens groups may be provided in four directions of up, down, left, and right with the direct viewing direction as the center. In this case, as shown in FIG. 15, the image GD in the direct viewing region is centered. By displaying the image GSU in the upper viewing area, the image GSD in the lower viewing area, the image GSL in the left side viewing area, and the image GSR in the right side viewing area, it is possible to obtain an image with high visibility. can.

Further, the composite surface in the composite unit is not limited to the partially transmitted and partially reflected surface, but is arranged so as to transmit the light flux emitted from the first lens group and totally reflect the light flux emitted from the second lens group. It may be a total reflection surface. With such a configuration, it is possible to suppress a decrease in the amount of light flux in the side view region.

Further, the same lens configuration may be used for all the lens groups of the first lens group and the plurality of second lens groups. With such a configuration, the design of the optical system for the endoscope can be simplified, and the parts constituting each lens group can be shared, so that the cost can be suppressed.

Of course, in addition to the above, various improvements and modifications may be made without departing from the gist of the present invention.

1 Optical system for endoscope 100 Endoscope 102 Operation part 104 Insertion part 106 Universal cord 107 Flexible part 108 Curved part 109 Curved operation knob 110 Tip part 120 Signal processing device 130 Display device A1 Axial light beam in direct view A2, A3 B1 Axial light beam in left side view B2, B3 Maximum angle light beam in left side view C1 Axial light beam in right side view C2, C3 Maximum angle light beam in right side view CL1a, CL3a Lens G1 1st lens group G2L, G2R 2nd lens group G3 3rd lens group L1a to L3e Lens PP Optical member Sim Imaging surface St Aperture aperture X Synthetic part XS1, XS2 Synthetic surface Z1 Optical axis Z2L of the 1st lens group, Z2R Optical axis of the 2nd lens group Z3 Optical axis of the 3rd lens group

Claims (16)

It is an optical system for endoscopes that can be viewed both directly and sideways.
The first lens group used only for direct vision and
A plurality of second lens groups having a negative lens on the most object side and used only for lateral vision,
With the third lens group shared by direct vision and lateral vision,
It has at least one planar composite surface that transmits the light beam emitted from the first lens group and reflects the light beam emitted from the second lens group, and is emitted from the first lens group by the composite surface. It consists of a compositing unit that synthesizes the light beam and the light beam emitted from the second lens group and causes them to enter the third lens group.
The luminous flux emitted from the first lens group and the luminous flux emitted from the second lens group are imaged on the same surface .
The second lens group is an optical system for an endoscope having two or more negative lenses continuously from the object side. The surface of one of the synthetic surface is formed, according to claim 1 Symbol placement endoscope optical system of the whole is part transmitting part reflecting surface. The optical system for an endoscope according to claim 1 or 2, wherein the third lens group has a third a-junction lens in which a positive lens and a negative lens are joined in order from the object side on the image side. The endoscope optical system according to any one of claims 1 to 3 , wherein the first lens group has a first a-junction lens in which a positive lens and a negative lens are joined in order from the object side. The focal length of the first lens group is f1,
When the combined focal length between the first lens group and the third lens group is F1
-1.5 <f1 / F1 <-1.1 ... (2)
The optical system for an endoscope according to any one of claims 1 to 4 , which satisfies the conditional expression (2) represented by. The focal length of the third lens group is f3,
When the combined focal length between the first lens group and the third lens group is F1
5 <f3 / F1 <12 ... (3)
The optical system for an endoscope according to any one of claims 1 to 5 , which satisfies the conditional expression (3) represented by. The Abbe number of the positive lens of the 3a junction lens is νd31,
When the Abbe number of the negative lens of the 3a junction lens is νd32.
38 <νd31-νd32 <58 ... (4)
The optical system for an endoscope according to claim 3, which satisfies the conditional expression (4) represented by. The refractive index of the positive lens of the third a junction lens is n31.
When the refractive index of the negative lens of the 3a junction lens is n32,
-0.45 <n31-n32 <-0.28 ... (5)
The optical system for an endoscope according to claim 3 or 7, which satisfies the conditional expression (5) represented by. The Abbe number of the positive lens of the first a junction lens is νd11.
When the Abbe number of the negative lens of the first a junction lens is νd12,
-40 <νd11-νd12 <-10 ... (6)
The optical system for an endoscope according to claim 4, which satisfies the conditional expression (6) represented by. The endoscope optical system according to any one of claims 1 to 9 , wherein the composite surface is tilted with respect to an axis perpendicular to the optical axis of the third lens group. -1.45 <f1 / F1 <-1.15 ... (2-1)
The optical system for an endoscope according to claim 5, which satisfies the conditional expression (2-1) represented by. 7 <f3 / F1 <10 ... (3-1)
The optical system for an endoscope according to claim 6, which satisfies the conditional expression (3-1) represented by. 40 <νd31-νd32 <56 ... (4-1)
The optical system for an endoscope according to claim 7, which satisfies the conditional expression (4-1) represented by. -0.43 <n31-n32 <-0.3 ... (5-1)
The optical system for an endoscope according to claim 8, which satisfies the conditional expression (5-1) represented by. -38 <νd11-νd12 <-12 ... (6-1)
The optical system for an endoscope according to claim 9, which satisfies the conditional expression (6-1) represented by. An endoscope provided with the optical system for an endoscope according to any one of claims 1 to 15.

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